1. Field of the Invention
The present invention relates to an apparatus for the expansion of tubulars, and in particular to an apparatus for expanding tubulars utilised in the oil and gas industry.
2. Description of the Related Art
Recent developments in the fields of exploration and production of hydrocarbons have led to the introduction of technology that enables the expansion of sections of tubing downhole. The tubing may take a number of forms including: casing, liner, sandscreens, packers and hangers. A variety of expansion tools and methods are known, and include the use of expansion mandrels. The expansion mandrel may be in the shape of a cone and may be forced through a section of tubing by the application of an appropriate force. Alternatively, the tubing may be expanded by the use of a rotary expansion tool, which typically comprises a number of expansion rollers which are urged radially outwardly while the tool is rotated within the tubing and advanced axially through the tubing.
Examples of rotary expansion tools and related methods of expanding tubing are disclosed in applicant's patent application WO 00\37766, the disclosure of which is incorporated herein by reference.
One difficulty experienced with known rotary expansion tools is the limited length of tubing that can be expanded by the expansion tool before the tool has to be replaced: this is due to a number of factors, including wear of the rollers and in particular the relatively short life of the roller bearings.
It is an object of at least one embodiment of the present invention to provide a method and apparatus for increasing the operating life of an expansion tool.